Ink jet printers have printheads that include a plurality of inkjets for ejecting liquid ink onto an image receiving member. The ink may be stored in reservoirs located within the printer. The ink ejected by a printhead may be aqueous, oil, solvent-based, UV curable gel ink, or an ink emulsion. The gel ink may be heated to a predetermined temperature to alter the viscosity of the ink so the ink is suitable for ejection by a printhead. Another form of ink used in inkjet printers is solid ink. Solid ink may be inserted into the printer in blocks, sticks, pellets, or pastilles. The solid ink is delivered to a melting device and melted to generate liquid ink that is delivered to a printhead. The melted ink may be collected in a reservoir before being supplied to one or more printheads through a conduit or the like.
A typical full width scan inkjet printer uses one or more printheads. Each printhead typically contains an array of individual nozzles for ejecting drops of ink across an open gap to an image receiving member to form an image. The image receiving member may be a continuous web of recording media, a series of media sheets, or the image receiving member may be a rotating surface, such as a print drum or an endless belt. Images printed on a rotating surface are later transferred to recording media by mechanical force in a transfix nip formed by the rotating surface and a transfix roller. In an inkjet printhead, individual piezoelectric, thermal, or acoustic actuators generate mechanical forces that expel ink through an orifice from an ink filled conduit in response to an electrical voltage signal, sometimes called a firing signal. The amplitude, or voltage level, of the signals affects the amount of ink ejected in each drop. The firing signal is generated by a printhead controller in accordance with image data. An inkjet printer forms a printed image in accordance with the image data by printing a pattern of individual ink drops at particular locations on the image receiving member. The locations where the ink drops landed are sometimes called “ink drop locations,” “ink drop positions,” or “pixels.” Thus, a printing operation can be viewed as the placement of ink drops on an image receiving member in accordance with image data.
In a printer in which ink is ejected onto a moving web, the web supply may run out or the web may break. Consequently, one or more printheads may inadvertently eject drops of ink on printer components. The printing process may have to be stopped as a result to enable the printer components to be cleaned. A similar problem may arise in printers capable of printing images on different widths of media. When the width of an ink image is wider than the media receiving the ejected ink, one or more printheads positioned beyond the edges of the media may eject ink onto printer components. Again, the printing process may have to be stopped to clean the printer components. Operating a printer to avoid such stoppages would be beneficial.